DESIGN, SAFETY AND FUEL DEVELOPMENTS FOR THE EFIT ACCELERATOR DRIVEN - - PowerPoint PPT Presentation

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DESIGN, SAFETY AND FUEL DEVELOPMENTS FOR THE EFIT ACCELERATOR DRIVEN SYSTEM WITH CERCER AND CERMET CORES W. Maschek 1 , C. Artioli 2 , X. Chen 1 , F. Delage 3 , A. Fernandez-Carretero 4 , M. Flad 1 , A. Fokau 7 , F. Gabrielli 1 , G. Glinatsis 2 ,

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

DESIGN, SAFETY AND FUEL DEVELOPMENTS FOR THE EFIT ACCELERATOR DRIVEN SYSTEM WITH CERCER AND CERMET CORES

  • W. Maschek1, C. Artioli2, X. Chen1, F. Delage3, A. Fernandez-Carretero4 , M. Flad1, A. Fokau7, F.

Gabrielli1, G. Glinatsis2, P. Liu 1, L. Mansani5, C. Matzerath Boccaccini1,C. Petrovich2, A. Rineiski1, M. Sarotto2, M. Schikorr1, V. Sobolev6, S. Wang 1,Y. Zhang7

1 Forschungszentrum Karlsruhe, IKET, P.O.Box 3640, D-76021 Karlsruhe, Germany 2 ENEA, Via Martiri di Montesole 4, IT-40129 Bologna, Italy 3 Commissariat à l’Energie Atomique (CEA) Cadarache, 13108 Saint Paul Lez Durance, France 4 JRC Institute for Transuranium Elements P.O. Box 2340, D-76125, Karlsruhe, Germany 5 AnsaldoNucleare, Corso F. M. Perron 25, I -16161 Genoa, Italy 6 SCK-CEN, Belgian Nuclear Research Centre, Boeretang 200, B-2400 Mol, Belgium 7 KTH, Dpt. of Nuclear and Reactor Physics, S-10691Stockholm, Sweden

Actinide and Fission Product Partitioning and Transmutation Tenth Information Exchange Meeting Mito, Japan 6-10 October 2008

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

I:

Introduction II: Fuels for Accelerator Driven Transmuters, Generation of the Fuel Data Base in DM 3 AFTRA and Recommendations on Fuels and Safety Limits III: The EFIT (European Facility for Industrial Transmutation) as CERCER and CERMET Option IV: AFTRA Safety Analyses for CERMET Cores VI: Conclusions

Content

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

EFIT, the European Facility for Industrial Transmutation developed within 6th FP EU EUROTRANS The Domain DM1 (DESIGN) responsible for overall design, integration and safety of EFIT The Domain DM3 (AFTRA) responsible for the fuel assessment and development AFTRA also involved in core design activities and safety studies for assessing individual fuels and provide recommendation on fuels Both CERCER and CERMET EFIT cores have been developed The CERCER core has been chosen as the reference core by DM1 and most extensive investigations on design and safety concentrate on this core The CERMET core has alternatively be developed by AFTRA I : Introduction

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

  • Solid Solution Fuel
  • (Pu,Am,Cm, Zr)O2-x or

(Pu,Am,Cm,Th)O2-x

  • CERMET
  • (Pu,Am,Cm)O2-x + Mo, Mo92, W, Cr or V
  • CERCER
  • (Pu,Am,Cm)O2-x + MgO

II : Fuels for Accelerator Driven Transmuters Selection Criteria:

  • Oxide fuels because of vast European experience
  • Fabrication
  • Feasibility: matrix volume fraction > 50%
  • Clad and coolant compatibility
  • Safety behavior
  • Coolant void worth
  • Reactivity loss
  • Burnup
  • Transmutation capability
  • Reprocessing (aqueous)
  • ………

Final AFTRA Recommendation :

1)

Mo-92 CERMET because of superior safety behaviour

2)

Backup solution : MgO CERCER because of better neutronic performance

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

Safety Issues and Fuel Limiting Temperatures Defence-in-Depth Categorization of Plant Conditions :

Requirement of ‚no melting‘ up to DBC Category 4 (restrictive limit taken because of uncertainties) Main reason for AFTRA recommendation for CERMET motivated by safety concerns in the light of limited data and phenomenological uncertainties in high temperature region (‚melting‘ as composite disintegration, eutectic formation,…. at much lower temperatures than MOX)

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

  • Arbeitsschritte

Specific CERCER Related Problems

1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 1E-14 1E-13 1E-12 1E-11 1E-10

M.S. signal (A) Tem perature (K)

Am Am O Am O

2

Np NpO NpO

2

1E-14 1E-13 1E-12 1E-11 1E-10 1E-9 1E-8

M.S. signal (A)

M g O Pu PuO PuO

2

  • MgO shows tendency for disintegration at

higher temperatures - Knudsen cell tests ITU

  • Safety behavior under un-clad conditions not

known

  • Potential for fuel/matrix separation
  • MgO shows a significant decrease

in the thermal conductivities at higher temperatures (1500 K) – CEA measurement

  • Irradiation leads to further

deterioration

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SLIDE 7

KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

Fuel Irradiation Experiments in Phenix & HFR Reactors

EUROTRANS Experiments : FUTURIX-FTA , HELIOS and BODEX

  • Demonstration of the fabrication feasibility
  • Determination of material properties
  • FUTURIX- FTA : Irradiation behaviour in fast

neutron environment for oxide, nitride, metallic fuels – for EUROTRANS only CERMET (Phenix)

  • HELIOS : Helium release mechanisms & swelling

in MA fuels (HFR)

  • BODEX : Helium build-up and release

mechanisms on inert matrices

  • Problem : Results of experiments expected at end
  • f EUROTRANS

FUTURIX 6 CERMET Pellet HELIOS 3 Pellet BODEX Pellet

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

Lead Coolant T91 Clad

T91 cladding temperature versus time to failure by creep rupture

0.0001 0.01 1 100 10000

T ime [h]

900 1000 1100 1200 1300

T [K ]

p= 1 Mpa p= 10 Mpa p= 5 Mpa

EFIT :

  • GESA treated

clad without conductivity reducing oxide layers

  • Use of optimized

clad for EFIT design

  • Derivation of failure data

based on LMP

  • Uncertainties in LMP for

fast transients

  • Uncertainties under HLM

conditions and irradiation

  • Other failure modes not

investigated Further Safety Related Boundary Conditions given by Clad and Pb Coolant

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

  • Target Unit Type:
  • Windowless with Mechanical

Pumps

  • Heat Sink below Free Level
  • Proton Beam:
  • 800 MeV; 20 mA
  • Proton Travel Depth in Lead

about 43 cm

  • Deposited Power and Irradiation

Damage:

  • 70% Proton Beam Power (11.2

MW)

  • Max dpa 100 to 130
  • Max Coolant Velocity:
  • About 1 m/s (except around

the pump) impeller)

  • Low Pressure Losses
  • About 50÷60 kPa
  • Temperature:
  • Primary Coolant Inlet 673 K
  • Max Average Target Coolant

793 K

  • Power = 400 MWth
  • Beam : 800 MeV, 20 mA
  • Keff = 0.97
  • Pool type reactor with hot leg

pump

  • No intermediate loop
  • Pb coolant
  • T-in / T-out = 673/753 K
  • Fuel : CERCER & CERMET
  • Clad = T91

III : The EFIT (European Facility for Industrial Transmutation)

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

The 42 : 0 Concept Fission Rate ≅ 42 kg/TWth

  • 42 kg (MA) / TWh

0 kg (Pu) / TWh f (fuel E = 45,7%)

E = Pu /( MA + Pu )

MA: (Np, Am, Cm)

Boundary Conditions for CERCER Core :

3 core zones for power flattening

Matrix ratio : 57 : 50 : 50 % / Max lin. pow. ≅ 200 : 180 : 180 W/cm

  • Max. fuel operating temperature 1650 K

Max clad operating temperature 823 K Lead coolant (velocity ~ 1 m/s; Tin = 673 K; Tout = 753 K) Residence time 3 years Pb corrosion could define limit GESA treatment !!! Limited reactivity loss over 3 years (constant beam power requirement) The CERCER EFIT Transmutation Concept

EFIT designed as a MA burner

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

The CERCER EFIT Operational and Safety Data

Safety Coefficients Transmutation Efficiency Power Profile EFIT MgO CERCER Core

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

The CERMET EFIT Transmutation Concept

Axial fuel, clad and coolant temperatures in peak power subassembly

EFIT Mo CERMET Core

Mo-92 Basis (Enrichment !)

AFTRA Mo-92 CERMET Core :

CERMET core fits into overall design of EFIT given by ANSALDO & ENEA (CERCER EFIT) Due to less favourable neutronic characteristics

  • f Mo-92 (higher n-absorption) Pu/MA ratio has

to be increased if same design parameters (pin, fuel/matrix volume fractions, subcriticalty) are taken as in CERCER core High Pu/MA ratio leads to less MA incineration & stronger reactivity loss Solution to achieve low Pu/MA : increase of fuel volume ratio via thicker pins respecting thermal- hydraulic and clad conditions ‚Fat‘ pins no problem for CERMET because of high thermal conductivity – safety assured High MA incineration achieved but 42:0 strategy slightly violated Low reactivity swing over burn-up

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

The CERMET EFIT Operational and Safety Data

Reactivity swing as function of (Pu/MA) ratio

0.955 0.96 0.965 0.97 0.975 0.98 0.985 0.5 1 1.5 2 2.5 3 k-eff time,years 3055-46/54 2966-40/60 2899-35/65

Burn-up calculation results for different Pu/MA ratios CERMET core safety parameters

Note : Void worth values given in tables serve as indicators (similar as in SFR safety)

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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

  • Subcriticality could be

eliminated (in contrast to Doppler)

  • Subcriticality is essential and

is ‘the’ stabilizing physical mechanism

Safety Concern :

  • Under DEC safety conditions
  • Elimination of significant part of

subcriticality in case of core degradation

  • Potential for power excursion
  • Analyses indicate the potential

for void consumption under severe conditions

IV : Safety Analyses for AFTRA CERMET EFIT Currently extensive and paramount safety analyses under way for CERCER EFIT For CERMET EFIT only limited analyses performed for most important transients to identify key safety issues of CERMET and identify differences to CERCER General impact of U-free fuels on global core dynamics and safety :

  • No prompt (negative) feedback

effects (Doppler)

  • Strong delayed (positive)

feedback effects by high reactivity worths (coolant void worths generally larger than subcriticality)

  • Deteriorated kinetics parameters
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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

3–zone

core with low power density of ~ 250 MW/m3

Natural convection flow ~ 40 %

Mo-92 CERMET 400 MWth EFIT low power density core

0,995 1 1,005 1,01 1,015 1,02

  • 2950
  • 2900
  • 2850

30 40 50 60 70 80 90 100

Power Reactivity

Time [s] 700 800 900 1000 1100 1200 1300 0,2 0,4 0,6 0,8 1 1,2 30 40 50 60 70 80 90 100

Maximal Coolant Temperature Maximal Cladding Temperature Maximal Fuel Temperature Maximal Coolant Velocity

Time [s]

Examples of Safety Analyses : ULOF

Slight power increase by 1.7 %

due to the positive coolant feedback

No pin failures

  • Max. fuel temperatures far below

the failure limits

  • Max. clad temperatures (1000K)

below failure limits (creep)

SIMMER-III Analyses of ULOF

  • Top : Power and reactivity trace
  • Bottom : Fuel, clad, coolant temperatures
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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

3–zone

core with high power density of ~ 500 MW/m3

Power stretching to increase

transmutation performance

In-pin pressure = 30 bars Investigation of pin failure and

failure propagation

Mo-92 CERMET 800 MWth EFIT high power density core

Examples of Safety Analyses : ULOF high power density core

Pin failure & void propagation & power

surge

  • Max. clad temperatures (1250K) above

failure limits (creep)

Coherence of clad & coolant

temperatures under ULOF conditions lead to propagation potential

SIMMER-III Analyses of ULOF

  • Top : Power and reactivity trace
  • Bottom : Void distribution
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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

  • The innermost SA-ring is blocked
  • UBA outcome depends on many parameters :
  • Gas plenum pressure, clad failure

temperature (gas release ), clad loss of mechanical strength, clad melting, fuel pin break-up, pellet/particle behavior, upper structure behavior

Mo-92 CERMET EFIT 400 MWth low power density core

Examples of Safety Analyses : UBA CERMET Core

Gas blow-down causes short reactivity/power

increase due the positive void feedback but rewetting prevents coherent failure propagation

Reactivity/power decrease in this special case due to

fuel sweep-out from the blocked core region

Investigations show that realistically subassembly

damage propagation to be expected until opening of larger fuel escape paths without power excursion

Note : phenomenology independent of 2D or 3D

simulation SIMMER-III Analyses of UBA

  • Top : Power and reactivity trace
  • Bottom : Material distribution
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KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

  • CERCER EFIT developed as reference design option
  • CERMET EFIT offers alternative, especially because of safety performance
  • Both CERCER and CERMET cores offer good transmutation performance
  • Future work on cores with different transmutation strategies
  • Further design optimization and assessment of power upgrading option
  • For fuels, the irradiation results of FUTURIX, BODEX and HELIOS are urgently

awaited

  • Based on current analyses and knowledge, fuels generally do not pose limit
  • n design and safety, but the T91 clad
  • CERMET fuel has very large margins to failure
  • Limited knowledge on fuel behavior under irradiation, transient and high

temperature conditions; ‘microphysics’ of fuel must be understood and modeled in codes

V : Conclusions

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SLIDE 19

KIT – die Kooperation von Forschungszentrum Karlsruhe GmbH und Universität Karlsruhe (TH)

  • For ADTs, high coolant reactivity feedback and lack of Doppler are features

to consider in safety analyses

  • Massive voiding only in case of extensive pin failures or introduction of

steam/water after a SGTR accident with coolant-coolant interaction (CCI)

  • For current EFIT design SIMMER analyses do not show massive pin-to-

pin failure propagation

  • For current design SIMMER analyses do not show introduction of steam

into the core after a SGTR

  • Needs for understanding fuel behavior under irradiation and impact on
  • perational conditions, transients and accidents
  • Needs for understanding ‘pin failure’ under various transient conditions
  • T91 creep failure data (short time phenomena, high temperature) and other

clad failure mechanisms to be investigated

  • Needs for extensive transient tests of advanced fuels and clad
  • Needs for code development

Conclusions (cont.)